Horsetooth Reservoir and the C-BT

Horsetooth Reservoir and the C-BT

Horsetooth Reservoir is a water storage facility located just west of Fort Collins, Colorado. The reservoir has a capacity of 156,735 acre feet of water, 25 miles of shoreline, and 1,900 surface acres. Horsetooth has more storage capacity than any other reservoir in the Colorado-Big Thompson East Slope distribution system. Water for the reservoir originates high in the Rocky Mountains in the Colorado River and flows through the Colorado-Big Thompson System. Flowing towards Horsetooth, the water diverts at the Flatirons Reservoir through the Hansen Feeder Canal just outside of the City of Loveland. After the water travels through the 13-mile canal, it ends up in Horsetooth Reservoir, but not all of it stops there. The Hansen Supply Canal takes some of the water from the reservoir and dumps it into Cache la Poudre River several miles north of Fort Collins.1

Horsetooth Reservoir and the Colorado Big-Thompson are perfect examples of the change of water usage over time. The reservoir began as a building project in 1946 and was completed in 1949. Water was first released in 1951. Northern Colorado Water Conservancy District (NCWCD) oversees the water for the reservoir and has kept detailed records of what the water is used for. In 1954, three years after the Horsetooth Reservoir first received water, agriculture used 98.6 percent of the water leaving a mere 1.4 percent for municipal purpose. Agriculture used 90 percent of the water until the 1970s when it fluctuated between the 80 and 90 percentile range. A more rapid decline followed in the 1990s dropping the difference to an average of about 60 percent for agricultural usage and 40 percent municipal. Since the 1990s, a little over half of the water from Horsetooth Reservoir has been used for agricultural purposes. These statistics are indicative of a changing society. (See the graph in the sidebar.)2

The City of Fort Collins wanted to be a part of the C-BT system as early as the 1950’s in order to meet the growing demand for water. With water from the C-BT and the Poudre River, Fort Collins has been largely successful in meeting all the demand except for the driest years (1977 and 2002). As a result, the City has more than doubled its water rights in the C-BT since the 1950s through the purchasing of units and the turning over of rights in developed land. This safeguard against drought with water from the C-BT has served the people of Fort Collins well and hopefully will continue to do so in the future.3

Horsetooth Reservoir, part of the Colorado-Big Thompson Project, first held water in 1951. C-BT water originally provided water for irrigation; now agricultural entities use only half of the water annually. Urban users claim the other half. Courtesy of Fort Collins Local History Archive, S01183

The natural basin west of Fort Collins that would become Horsetooth Reservoir, circa 1951. Courtesy of Fort Collins History Connection Horsetooth Reservoir, circa 1951. Courtesy of Fort Collins History Connection

Water Deliveries from Horsetooth Reservoir from 1954 to 2013.Courtesy of Northern Colorado Water Conservancy District